System and method for facilitating trading in an electronic market

ABSTRACT

A method and system for facilitating trading of financial instruments in a market are provided. The system comprises a server and an interface. The interface is configured to enable buy orders and sell orders to be entered. Each order has a price, a volume, and an entry time and relates to a respective futures contract The server is configured to match received buy orders having a first price to received sell orders having the first price. The match is effected by ensuring that the prices match, and then using the volume and entry time for each buy order and each sell order to assign a volume weight and a time weight, and then using the volume weights and the time weights to determine each match. The server uses the matches to complete respective trades. The volume and time weights may be adjusted based on market conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No. 11/537,733, filed Oct. 2, 2006, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of financial markets. More particularly, the invention relates to the trading of financial instruments, such as futures contracts, options contracts, forward contracts, or spot contracts, whose underlying assets may include rates, bonds, commodities, currencies, energy, equities, interest rates, or metals.

2. Related Art

Financial markets support trading in multiple financial instruments. The central dynamics of the market in which each instrument operates and trades will depend upon the individual characteristics of the instrument.

All markets which provide a periodic or continuous auction for the matching of buy orders and sell orders through a central order book employ a trading algorithm which prescribes how matching occurs. As markets have adopted electronic trading, in their move from the traditional exchange trading floor to the screen, exchanges have sought to electronically replicate the characteristics present in the trading floor environment. Furthermore, the adoption of electronic trading has enabled and continues to enable further development of such auction-based functionality.

In the exchange-based derivative markets, traders of equity derivative instruments have become accustomed to a time priority algorithm, in which orders of the same price are prioritized for matching according to the time they entered the central order book.

Certain exchange-traded interest rate derivative contracts, such as, in particular, short term interest rate (“STIR”) contracts, such as Short Sterling, Euribor and Eurodollar futures, reflect interest rate expectations stretching out several years in periodic, often quarterly, intervals. Interest rate expectations over time may be reflected graphically by what is known as the yield curve. Individual movements along each point of the yield curve can often be subtle, as the market establishes its expectations of future interest rates. As a consequence, the trading algorithm employed when exchange trading moved from floor to screen was designed to extract maximum liquidity from a market with these characteristics. Accordingly, the major STIR markets have employed a volume pro-rata algorithm, which is designed to distribute trading opportunities amongst a greater number of traders, thus encouraging wider participation and henceforth greater levels of liquidity in the market.

As electronic markets have evolved, access has become easier and more cost effective, and contracts which were traded on a single trading floor of one of the London or Chicago exchanges are now available globally through an electronic trading screen. As a result, traders have access to multiple markets through a single screen and are able to seek the most liquid instruments, given any particular global macro-economic circumstance. In response to this evolution in electronic markets, exchanges have found that the traditional characteristics that originally governed the dynamics of the floor based markets, and their early electronic replacements, also need to evolve. This evolution will ensure that the market maximizes opportunities for as wide a range of market participants as possible, regardless of their respective heritages as traders. In order to remain competitive, exchanges need to be in a position to rapidly respond to evolutions in the marketplace. This includes developing an ability to rapidly adapt the characteristics of the trading algorithm to suit new market dynamics and to accommodate new market participants. Accordingly, the present invention is intended to address this problem.

SUMMARY OF THE INVENTION

In one aspect, the invention provides a system for facilitating trading of futures contracts in a market. The system comprises a server at which futures contracts are actively traded and an interface in communication with the server. The interface is configured to enable at least one of a buy order and a sell order to be entered. Each buy order and each sell order has a price, a volume, and an entry time and relates to a respective futures contract.

The server is configured to receive a plurality of buy orders and sell orders from the interface, and to match buy orders relating to a first futures contract and having a first price to sell orders relating to the first futures contract and having the first price. The match is effected by using the volume and entry time for each buy order and each sell order to assign a volume weight and a time weight, and then using the assigned volume weights and the assigned time weights to determine each match. The server is further configured to use each determined match to complete a respective trade.

The system may be further configured to determine each match according to a first algorithm which is expressible as follows:

$f_{n} = \frac{{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}\; v_{r}} \right)} + {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}\; r} \right)}}{w_{v} + w_{t}}$

In the above equation for the first algorithm, each buy or sell order relating to the first futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. The time offset C may be set equal to 1.

Alternatively, the server may be further configured to determine each match according to a second algorithm which is expressible as follows:

$f_{n} = {\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}\; v_{r}} \right)^{\frac{w_{v}}{S}} \times \left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}\; r} \right)^{\frac{w_{t}}{S}}}$

In the above equation for the second algorithm, each buy or sell order relating to the first futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; S=a smoothing factor; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. The time offset C may be set equal to 1.

Each buy order and each sell order may be assigned at least a third weight value relating to a third characteristic. The server may be further configured to use at least the assigned third weight values in conjunction with the assigned volume weights and the assigned time weights to determine each match. The third characteristic may include an association with a trader, and the third weight value may relate to a preference value associated with the trader.

The server may be further configured to assign the volume weights and the time weights by using observable data relating to the market. The server may also be further configured to adjust at least one of the previously assigned volume weights and the time weights by using observable data relating to the market.

In another aspect, the invention provides a method of trading of futures contracts in a market. The method includes the steps of enabling a plurality of users to enter buy orders and sell orders, each buy order and each sell order having a price, a volume and an entry time and relating to a respective futures contract; assigning a volume weight and a time weight to each buy order relating to a first futures contract and having a first price based on its respective volume and entry time; assigning a volume weight and a time weight to each sell order relating to the first futures contract and having the first price based on its respective volume and entry time; matching buy orders having the first price to sell orders having the first price using the assigned respective volume weights and time weights; and using the matched buy orders and sell orders to complete at least one trade.

The matching step may further include using the assigned respective volume weights and time weights according to a first algorithm which is expressible as follows:

$f_{n} = \frac{{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}\; v_{r}} \right)} + {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}\; r} \right)}}{w_{v} + w_{t}}$

In the above equation for the first algorithm, each buy or sell order relating to the first futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. The time offset C may be set equal to 1.

Alternatively, the matching step may further include using the assigned respective volume weights and time weights according to a second algorithm which is expressible as follows:

$f_{n} = {\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}\; v_{r}} \right)^{\frac{w_{v}}{S}} \times \left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}\; r} \right)^{\frac{w_{t}}{S}}}$

In the above equation for the second algorithm, each buy or sell order relating to the first futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; S=a smoothing factor; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. The time offset C may be set equal to 1.

The method may further include the step of assigning at least a third weight value to each buy order and to each sell order. The third weight value may relate to a third characteristic. The matching step may further include matching buy orders having the first price to sell orders having the first price using the assigned respective volume weights, time weights, and at least third weight values. The third characteristic may include an association with a trader and the third weight value may relate to a preference value associated with the trader.

The step of assigning the volume weight and the time weight to each buy order may further include assigning the volume weight and the time weight to each buy order by using observable data relating to the market. The method may further include the step of, for at least one buy order, adjusting at least one of the previously assigned volume or time weights by using observable data relating to the market. Similarly, the step of assigning the volume weight and the time weight to each sell order may further include assigning the volume weight and the time weight to each sell order by using observable data relating to the market. The method may further include the step of adjusting at least one of the previously assigned volume or time weights by using observable data relating to the market.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a system for facilitating trade matching of futures contracts according to a preferred embodiment of the invention.

FIGS. 2 a and 2 b are flow charts that illustrates a method of facilitating trade matching of futures contracts according to a preferred embodiment of the invention.

FIG. 3 is a graph that, using the first algorithm, illustrates a comparison between a pure volume pro-rata allocation, a pure time pro-rata allocation, and an equally weighted time and volume pro-rata allocation for matching buy orders to sell orders.

FIG. 4 is a graph that, using the second algorithm, illustrates a comparison between a pure volume pro-rata allocation, a pure time pro-rata allocation, and an equally weighted time and volume pro-rata allocation using index weighting and a smoothing factor equal to one for matching buy orders to sell orders.

FIG. 5 is a graph that, using the second algorithm, illustrates a comparison between a volume-biased pro-rata allocation, a time-biased pro-rata allocation, and an equally weighted time and volume pro-rata allocation using a higher index value and a smoothing factor equal to one for matching buy orders to sell orders.

FIG. 6 is a graph that, using the second algorithm, illustrates a comparison between three different smoothing factors as applied to an equally weighted time and volume pro-rata allocation using an index value equal to one for matching buy orders to sell orders.

FIG. 7 is a graph that, using the second algorithm, illustrates a comparison between applying a preferencing factor or not applying a preferencing factor for an equally weighted time and volume pro-rata allocation using an index value equal to one for matching buy orders to sell orders.

FIG. 8 is a graph that, using the first algorithm, illustrates a comparison between three different time offset factors as applied to a pure time pro-rata allocation for matching buy orders to sell orders.

DETAILED DESCRIPTION OF THE INVENTION

The essence of the invention is to seamlessly blend variable elements of volume and time into a single trading algorithm. The degree of bias, or weighting, given to each of these distinct elements can be controlled through selectable parameter settings within the algorithm, enabling a change to the market's matching characteristics with the ease of configuration change rather than the expensive process of software redevelopment and change, as is the case today. Furthermore, this multidimensional approach, which in a preferred embodiment includes the two dimensions of volume and time, may include a third dimension which gives a weighting towards particular market participants who carry out a pre-defined or specialized role in the market, such as, for example, a lead market maker.

Further benefits of the algorithm enable the dynamics of the market to be modified from time to time by:

-   -   the setting of configuration parameters according to observed         changes in the market.     -   continuous or periodic feedback: allowing targets to be set for         the participation profile which automatically feedback into the         algorithm and adjust the algorithm's weightings to ensure the         desired allocation across particular participant groups.         Different dynamics may be set to operate at different points in         the trading day; for example, at market open, during the morning         session, during the afternoon session, and at market close.         Finally, the algorithm enables the gradual introduction of new         elements into the central market's matching dynamics without         running the risk of unsettling existing dynamics through too         large a single step.

The invention relates to the field of financial markets. More particularly, the invention relates to the automated matching of buy orders and sell orders through periodic auction or continuous auction in a central order book. Such order books are traditionally implemented by regulated electronic stock exchanges and derivatives exchanges. More recently, off-exchange electronic multi-lateral trading facilities (“MTF”) have begun to develop, offering similar central order book functionality.

In one aspect, the invention provides a system for facilitating trading of futures contracts in a market. The system comprises a server at which interest rate futures are actively traded and an interface that communicates with the server. The interface is configured to enable at least one of a buy order and a sell order to be entered. Each buy order and each sell order has a price, a volume, and an entry time and relates to a respective futures contract. The server is configured to receive from the interface a plurality of buy orders and sell orders, and the server is further configured to store the received buy orders and sell orders in a central order book. All newly received orders, also referred to as incoming orders, are presented to the central order book for matching. Incoming buy orders are presented for matching with sell orders stored in the order book, and incoming sell orders are presented for matching with buy orders stored in the order book. If a match does not occur because the matching criteria have not been met, the server can be configured to store the incoming order in the order book together with that order's price, volume, and entry time. Stored orders are also referred to as resting orders. The server is further configured to match buy orders relating to a first futures contract and having a first price to sell orders relating to the first futures contract and having the first price. The match is effected by first ensuring a price match between the buy order and the sell order, and then using the volume and entry time for each buy order and each sell order to calculate a volume factor and a time factor and to assign a volume weight and a time weight, and then using the volume weights and the time weights to determine each match. The server is further configured to use each determined match to complete a respective trade.

The system may be further configured to determine each match according to a first algorithm which is expressible as follows:

$f_{n} = \frac{{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)} + {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}}{w_{v} + w_{t}}$

In the above equation for the first algorithm, each buy or sell order relating to the first futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. The time offset C may be set equal to 1.

Referring also to FIG. 8, the time offset affects the gradient of the time factor profile. A higher time offset value will reduce the difference in relative allocation between earlier and later resting orders. FIG. 8 provides a comparison of three time offset values to illustrate the effect upon the allocation given to later orders relative to earlier orders—the earliest order being the leftmost, with n=1; and the latest order being the rightmost, with n=10.

Alternatively, the server may be further configured to determine each match according to a second algorithm which is expressible as follows:

$f_{n} = {{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)}^{\frac{w_{v}}{S}} \times {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}^{\frac{w_{t}}{S}}}$

In the above equation for the second algorithm, each buy or sell order relating to the futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C =a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; S=a smoothing factor; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. Referring also to FIG. 8, the time offset C may be set equal to 1.

Each buy order and each sell order may be assigned at least a third weight value relating to a third characteristic. The server may be further configured to use at least the assigned third weight values in conjunction with the assigned volume weights and the assigned time weights to determine each match. The third characteristic may include an association with a trader, and the third weight value may relate to a preference value associated with the trader.

The server may be further configured to assign the volume weights and the time weights by using observable data relating to the market. The server may also be further configured to adjust at least one of the previously assigned volume weights and the time weights by using observable data relating to the market.

In another aspect, the invention provides a method of trading of futures contracts in a market. The method includes the steps of enabling a plurality of users, such as traders to enter buy orders and sell orders, each buy order and each sell order having a price, a volume, and an entry time and relating to a respective futures contract; assigning a volume weight and a time weight to each buy order relating to a first futures contract based on its respective volume and entry time; assigning a volume weight and a time weight to each sell order relating to the first futures contract based on its respective volume and entry time; matching buy orders to sell orders by first ensuring that the price of the buy order matches the price of the sell order and then using the assigned respective volume weights and time weights; and using the matched buy orders and sell orders to complete at least one trade.

The matching step may further include using the assigned respective volume weights and time weights according to a first algorithm which is expressible as follows:

$f_{n} = \frac{{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)} + {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}}{w_{v} + w_{t}}$

In the above equation for the first algorithm, each buy or sell order relating to the first futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. Referring also to FIG. 8, the time offset C may be set equal to 1.

Alternatively, the matching step may further include using the assigned respective volume weights and time weights according to a second algorithm which is expressible as follows:

$f_{n} = {{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)}^{\frac{w_{v}}{S}} \times {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}^{\frac{w_{t}}{S}}}$

In the above equation for the second algorithm, each buy or sell order relating to the first futures contract is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first futures contract; v_(n)=a volume of the n^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; S=a smoothing factor; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order. Referring also to FIG. 8, the time offset C may be set equal to 1.

The method may further include the step of assigning at least a third weight value to each buy order and to each sell order. The third weight value may relate to a third characteristic. The matching step may further include matching buy orders to sell orders using the assigned respective volume weights, time weights, and at least third weight values. The third characteristic may include an association with a trader and the third weight value may relate to a preference value associated with the trader.

The step of assigning the volume weight and the time weight to each buy order may further include assigning the volume weight and the time weight to each buy order by using observable data relating to the market. The method may further include the step of, for at least one buy order, adjusting at least one of the previously assigned volume or time weights by using observable data relating to the market. Similarly, the step of assigning the volume weight and the time weight to each sell order may further include assigning the volume weight and the time weight to each sell order by using observable data relating to the market. The method may further include the step of, for at least one sell order, adjusting at least one of the previously assigned volume or time weights by using observable data relating to the market.

Referring to FIG. 1, a block diagram illustrates an electronic trading system 100 according to a preferred embodiment of the present invention. The system includes one or more servers 105, also referred to as a trading host 105, and one or more trader interfaces 110, also referred to as an Individual Trading Mnemonic (ITM) 110. The trading host 105 is preferably implemented by the use of one or more general purpose computers, such as, for example, a Sun Microsystems F15k. Each ITM 110 is also preferably implemented by the use of one or more general purpose computers, such as, for example, a typical personal computer manufactured by Dell, Gateway, or Hewlett-Packard. Each of the trading host 105 and the ITM 110 can include a microprocessor. The microprocessor can be any type of processor, such as, for example, any type of general purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, an application-specific integrated circuit (ASIC), a programmable read-only memory (PROM), or the like. The trading host may use its microprocessor to read a computer-readable medium containing software that includes instructions for carrying out one or more of the functions of the trading host 105, as further described below.

Each of the trading host 105 and the ITM 110 can also include computer memory, such as, for example, random-access memory (RAM). However, the computer memory of each of the trading host 105 and the ITM 110 can be any type of computer memory or any other type of electronic storage medium that is located either internally or externally to the trading host 105 or the ITM 110, such as, for example, read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, an erasable programmable read-only memory (EPROM), an electrically-erasable programmable read-only memory (EEPROM), a computer-readable medium, or the like. According to exemplary embodiments, the respective RAM can contain, for example, the operating program for either the trading host 105 or the ITM 110. As will be appreciated based on the following description, the RAM can, for example, be programmed using conventional techniques known to those having ordinary skill in the art of computer programming. The actual source code or object code for carrying out the steps of, for example, a computer program can be stored in the RAM. Each of the trading host 105 and the ITM 110 can also include a database. The database can be any type of computer database for storing, maintaining, and allowing access to electronic information stored therein. The trading host 105 preferably resides on a network, such as a local area network (LAN), a wide area network (WAN), a virtual private network (VPN), or the Internet. The ITM 110 preferably is connected to the network on which the host server resides, thus enabling electronic communications between the trading host 105 and the ITM 110 over a communications connection, whether locally or remotely, such as, for example, an Ethernet connection, an RS-232 connection, or the like.

Referring to FIGS. 2 a and 2 b, flow charts 200 and 250 illustrate a method of facilitating trading of futures contracts according to a preferred embodiment of the present invention. For flow chart 200, in the first step 205, the trading host 105 receives incoming buy orders relating to a particular futures contract. At steps 210 and 215, a price match is determined for the incoming buy order against the sell orders resting in the order book. In general, with all trading algorithms, the highest bid (buy) prices and the lowest offer (sell) prices have priority over other orders at different prices in the order book. A price match occurs by matching the incoming buy order against all resting sell orders in the order book at the best market price level. If there is no price match for the incoming buy order, then the buy order, its price, its volume, and its entry time are stored at step 218 with the other resting buy orders in the order book. At step 220, the tradable volume is determined as the minimum of the total volume of resting sell orders in the order book or the volume of the incoming buy order.

At step 225, the volume factors and time factors are calculated for each resting sell order, according to their individual volumes and the individual times at which they entered the order book. At step 230, the selected smoothing factor (if applicable), the volume weight parameter, and the time weight parameter are assigned, and a pro-rata factor and allocation are determined for each resting sell order using an appropriate algorithm. Then, at step 235, all resting sell orders are sorted by pro-rata factor. At step 240, the tradable volume is distributed among the resting sell orders in accordance with the allocation determined in step 230. Step 240 is repeated until all tradable volume is exhausted, and the trades are then completed on the basis of these matches. Finally, at step 245, the weight parameters, the smoothing factor, and the time offset may be optionally adjusted based on observations relating to market conditions and trends.

Referring to FIG. 2 b, a similar process is illustrated for matching incoming sell orders to resting buy orders. In the first step 255, the trading host 105 receives incoming sell orders relating to a particular futures contract. At steps 260 and 265, a price match is determined for the incoming sell order against the buy orders resting in the order book. In general, with all trading algorithms, the highest bid (buy) prices and the lowest offer (sell) prices have priority over other orders at different prices in the order book. A price match occurs by matching the incoming sell order against resting buy orders in the order book at the best market price level. If there is no price match for the incoming sell order, then the sell order, its price, its volume, and its entry time are stored at step 268 with the other resting sell orders in the order book. At step 270, the tradable volume is determined as the minimum of the total volume of resting buy orders in the order book or the volume of the incoming sell order.

At step 275, the volume factors and time factors are calculated for each resting buy order, according to their individual volumes and the individual times at which they entered the order book. At step 280, the selected smoothing factor (if applicable), the volume weight parameter, and the time weight parameter are assigned, and a pro-rata factor and allocation are determined for each resting buy order using an appropriate algorithm. Then, at step 285, all resting buy orders are sorted by pro-rata factor. At step 290, the tradable volume is distributed among the resting buy orders in accordance with the allocation determined in step 280. Step 290 is repeated until all tradable volume is exhausted, and the trades are then completed on the basis of these matches. Finally, at step 295, the weight parameters, the smoothing factor, and the time offset may be optionally adjusted based on observations relating to market conditions and trends.

The volume factor is calculated in accordance with a volume pro-rata method. Volume pro-rata matching allocates incoming orders against eligible resting orders in proportion to the amount of volume of each individual resting order has relative to the total combined volume of all eligible resting orders in the order book. Each unit of volume is termed a “lot”. For each resting order n with volume v_(n) lots in a total of N orders, the volume factor is calculated as follows:

$\begin{matrix} {{{VolumeFactor}(n)} = \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}}} & {{Equation}\mspace{14mu} 1} \end{matrix}$

The volume of all resting and incoming orders will comprise a whole number of lots. In order to account for situations where a fraction of a lot is allocated to the incoming orders, trading hosts have conventionally employed a method of rounding. For example, the trading host may employ a method of rounding down allocations greater than one unit and rounding up allocations of less than one unit. Orders are matched starting with the largest allocation until all incoming orders are fulfilled. Subsequent passes may be necessary if all tradable volume is not fulfilled on the first pass. Examples provided in this application will use this method of rounding and allocation.

Table 1 below shows a typical volume pro-rata allocation of a 400 lot buy order against N=10 resting sell orders in the central order book.

TABLE 1 Volume (v) Volume Time (n) Trader (lots) Factor Allocation (lots) 1 AAA 200 8% (8% × 400 =) 32 2 BBB 200 8% (8% × 400 =) 32 3 CCC 100 4% (4% × 400 =) 16 4 DDD 100 4% (4% × 400 =) 16 5 EEE 50 2% (2% × 400 =) 8  6 FFF 50 2% (2% × 400 =) 8  7 GGG 100 4% (4% × 400 =) 16 8 HHH 200 8% (8% × 400 =) 32 9 JJJ 500 20%  (20% × 400 =) 80  10 KKK 1000 40%  (40% × 400 =) 160 Total 2500 400

Time priority matching simply allocates the incoming order amongst the eligible resting orders, giving a greater allocation to those resting orders which entered the order book first. Table 2 below shows the time priority allocation of a 400 lot buy order against N=10 resting sell orders (sorted by time) in the central order book.

TABLE 2 Volume (v) Allocation Time (n) Trader (lots) (lots) 1 AAA 200 200 2 BBB 200 200 3 CCC 100 0 4 DDD 100 0 5 EEE 50 0 6 FFF 50 0 7 GGG 100 0 8 HHH 200 0 9 JJJ 500 0 10 KKK 1000 0 Total 2500 400

Time pro-rata is a key element of the present invention and an innovative variation on the time priority concept. The time factor is calculated in accordance with the time pro-rata method. Eligible resting orders are allocated a proportion of the incoming order on based upon the time they entered the order book relative to the time other eligible resting orders entered the order book. The earlier the order entered the order book, the greater the allocation. This differs from the existing time priority concept, in that all orders have the potential to receive an allocation against the incoming order.

For each resting order n with volume v lots in a total of N orders (sorted in order of time entered into the order book, with n=1 being the first order entered and n=N being the last order entered), the time pro-rata factor is calculated using Equation 2 below. C is a time offset and may be set equal to 1.

$\begin{matrix} {{{TimeFactor}(n)} = \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r}} & {{Equation}\mspace{14mu} 2} \end{matrix}$

Table 3 below provides a simplified time pro-rata allocation of a 400 lot buy order against N=10 resting sell orders (sorted by time) in the central order book. It is noted that in operation, the allocation to each resting sell order n cannot exceed the volume v of each order. This situation does not arise in the example below, but where it does arise, subsequent passes of the allocation will be required to fulfill all of the incoming order.

TABLE 3 Volume (v) Time Allocation Time (n) Trader (lots) Factor (lots) 1 AAA 200 18.2% (18.2% × 400 =) 73 2 BBB 200 16.4% (16.4% × 400 =) 66 3 CCC 100 14.5% (14/5% × 400 =) 59 4 DDD 100 12.7% (12.7% × 400 =) 51 5 EEE 50 10.9% (10.9% × 400 =) 44 6 FFF 50 9.1% (9.1% × 400 =) 36 7 GGG 100 7.3% (7.3% × 400 =) 29 8 HHH 200 5.5% (5.5% × 400 =) 21 9 JJJ 500 3.6% (3.6% × 400 =) 14 10 KKK 1000 1.8% (1.8% × 400 =) 7 Total 2500 400

Combining the Volume Pro-Rata element and the Time Pro-Rata element into a single algorithm, and governing the weight or bias of each element, enables the market's central matching characteristics to be modified and offers greater flexibility to rapidly respond to evolutions in central market dynamics. Two methods are provided for combining the volume pro-rata and time pro-rata elements into a single algorithm:

-   -   Multiple Weighting (the first algorithm): The simpler of the two         methods provides a mechanism for multiplying each of the         elements by a weighting factor, which will govern the bias of         each respective element. The elements are then combined through         simple arithmetic addition.     -   Index Weighting (the second algorithm): This method affords a         greater level of control over the shape of the allocation         profile. The bias towards any element is controlled through         raising each element to the power of its respective weighting.         The elements are subsequently combined through multiplication.         Furthermore, this method allows the allocation profile to be         smoothed or exaggerated by employing a smoothing factor. The         result is then normalized.

The multiple weighting method is implemented according to the following description. For each resting order n with volume v_(n) lots in a total of N orders (sorted in order of time entered into the order book, with n=1 being the first order entered and n=N being the last order entered), the pro-rata factor f_(n) is calculated as follows:

$\begin{matrix} {f_{n} = \frac{{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)} + {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}}{w_{v} + w_{t}}} & {{Equation}\mspace{14mu} 3} \end{matrix}$

The allocation A_(n) for each resting order n against incoming order of volume R lots is calculated as follows:

A _(n)=MIN(v _(n) ,f _(n) ×R)   Equation 4

The MIN( ) function in Equation 4 ensures that the allocation for resting order n does not exceed the volume v of the order.

KEY—Parameters

-   N Number of Resting Buy (Sell) Orders     -   Sorted by Time—each n=1 (first) to N (last) -   v_(n) Volume of Each Resting Order n -   w_(v) Weighting of Volume Pro-Rata Element -   w_(t) Weighting of Time Pro-Rata Element -   C Time offset (generally set to 1) -   f_(n) Pro-rata factor for Resting Buy (Sell) Order n

A_(n) Allocation for Resting Buy (Sell) Order n

-   R Incoming Sell (Buy) Order Volume

Through controlling the parameters above, the allocation of the incoming order to the resting orders may be governed accordingly. Table 4 below demonstrates the allocation of an incoming buy order for 400 lots against N=10 resting sell orders in the central order book, where the respective weightings for the volume and time elements are:

-   -   Volume W_(v)=1; Time W_(t)=0 (equivalent to pure Volume         Pro-Rata)     -   Volume W_(v)=0; Time W_(t)=1 (equivalent to pure Time Pro-Rata)     -   Volume W_(v)=1; Time W_(t)=1 (equal weighting to both volume and         time elements)

TABLE 4 W_(v) = 1; W_(v) = 0; W_(v) = 1; Resting W_(t) = 0 W_(t) = 1 W_(t) = 1 Order Volume Time Equally Time Volume Pro-Rata Pro-Rata Weighted (n) Trader (v) (lots) Allocation Allocation Allocation 1 AAA 200 32 73 53 2 BBB 200 32 66 49 3 CCC 100 16 59 38 4 DDD 100 16 51 33 5 EEE 50 8 44 25 6 FFF 50 8 36 22 7 GGG 100 16 29 22 8 HHH 200 32 21 26 9 JJJ 500 80 14 48 10 KKK 1000 160 7 84 Total 2500 400 400 400

Referring also to FIG. 3, the data shown in Table 4 is depicted graphically to provide a visualization of how the allocation profile against the resting orders is altered using the parameters. The solid line (W_(v)=1, W_(t)=0) shows a pure volume pro-rata allocation, thus favoring orders n=9 and n=10, which have the largest volume. The dotted line (W_(v)=0, W_(t)=1) shows a pure time pro-rata allocation, thus favoring those orders which entered the market first, independently of their size. However, by equally weighting each element through W_(v) and W_(t), the resultant profile allocates the incoming order among the resting orders according to both their position in the order book and their relative volume. This is depicted through the broken line (W_(v)=1, W_(t)=1). In balancing the two elements, the market can be configured to appeal to traders who improve the market price by holding one of the earlier orders in the order book, and also to appeal to traders who offer sizable liquidity to the market by holding the larger volume orders. Alternatively, to favor the time element, yet still reward, but to a lesser degree, those that enter larger volume orders into the market, for example, a relative weighting of W_(v)=1, W_(t)=3 (not shown in FIG. 3) may be chosen to give a 75% preference to the time weighting parameter.

The index weighting method is implemented according to the following description. For each resting order n with volume v_(n) lots in a total of N orders (sorted in order of time entered into the order book, with n=1 being the first order entered and n=N being the last order entered), the pro-rata factor f_(n) is calculated as follows:

$\begin{matrix} {f_{n} = {{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)}^{\frac{w_{v}}{S}} \times {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}^{\frac{w_{t}}{S}}}} & {{Equation}\mspace{14mu} 5} \end{matrix}$

The allocation A_(n) for each resting order n against incoming order of volume R lots is calculated as follows:

$\begin{matrix} {A_{n} = {{MIN}\left( {v_{n},{\frac{f_{n}}{\sum\limits_{r = 1}^{N}f_{r}} \times R}} \right)}} & {{Equation}\mspace{14mu} 6} \end{matrix}$

KEY—Parameters

-   N Number of Resting Buy (Sell) Orders     -   Sorted by Time—each n=1 (first) to N (last) -   v_(n) Volume of Each Resting Order n -   w_(v) Weighting of Volume Pro-Rata Element -   w_(t) Weighting of Time Pro-Rata Element -   C Time offset (generally set to 1) -   S Smoothing factor (smoothing increases with S) -   f_(n) Pro-rata factor for Resting Buy (Sell) Order n -   A_(n) Allocation for Resting Buy (Sell) Order n -   R Incoming Sell (Buy) Order Volume

Referring to FIG. 4 and Table 5 below, a profile of the allocation against the resting orders is altered as shown using the parameters. Similarly as in the multiple weighting method described above, a volume weight parameter W_(v) of one (1) and a time weight parameter W_(t) of zero (0) provides a pure volume pro-rata algorithm, and a volume weight parameter W_(v) of zero (0) and a time weight parameter W_(t) of one (1) provides a pure time pro-rata algorithm. Equally weighting each parameter with a value of one (1) provides a profile which allocates the incoming order amongst the resting orders according to both their position in the order book and their relative volume.

TABLE 5 W_(v) = 1; W_(v) = 0; W_(v) = 1; Resting W_(t) = 0 W_(t) = 1 W_(t) = 1 Order Volume Time Equally Time Volume Pro-Rata Pro-Rata Weighted (n) Trader (v) (lots) Allocation Allocation Allocation 1 AAA 200 32 73 91 2 BBB 200 32 65 82 3 CCC 100 16 58 36 4 DDD 100 16 51 31 5 EEE 50 8 44 13 6 FFF 50 8 36 11 7 GGG 100 16 29 18 8 HHH 200 32 22 27 9 JJJ 500 80 15 46 10 KKK 1000 160 7 45 Total 2500 400 400 400 However, the index method provides a greater level of control over the shape of the allocation profile, as compared with the multiple weighting method. Referring also to FIG. 5 and Table 6 below, it may be seen that higher order parameter values for the volume weights and time weights offer a greater bias towards larger volume orders or earlier orders as W_(v) and W_(t) are adjusted respectively.

TABLE 6 W_(v) = 2; W_(v) = 1; W_(v) = 2; Resting W_(t) = 1 W_(t) = 2 W_(t) =2 Order Volume Bias Time Bias Equally Time Volume Pro-Rata Pro-Rata Weighted (n) Trader (v) (lots) Allocation Allocation Allocation 1 AAA 200 62 141 145 2 BBB 200 56 114 118 3 CCC 100 12 45 23 4 DDD 100 10 35 17 5 EEE 50 2 12 3 6 FFF 50 1 8 2 7 GGG 100 6 11 5 8 HHH 200 19 12 13 9 JJJ 500 77 15 37 10 KKK 1000 155 7 37 Total 2500 400 400 400

The index method also provides flexibility over the smoothness of the allocation profile. In each of FIGS. 4 and 5, a smoothing factor S of one (1) is used for both the volume weight parameter and the time weight parameter. Referring to FIG. 6 and Table 7 below, it is seen that even with equally weighted volume and time elements (in this example, both weight parameters are set equal to 1), by increasing the smoothing factor value of S, the profile of allocation of the incoming order over the resting orders in the central limit order book will be smoothed, or more evenly distributed. Ultimately, increasing the smoothing factor will evenly distribute the incoming order over all the resting orders, subject to a maximum allocation of their individual volumes v.

TABLE 7 Resting W_(v) = 1; W_(v) = 1; W_(v) = 1; Order W_(t) = 1 W_(t) = 1 W_(t) = 1 Time Volume Smoothing = Smoothing = Smoothing = (n) Trader (v) (lots) 1 2 3 1 AAA 200 91 64 55 2 BBB 200 82 61 54 3 CCC 100 36 40 41 4 DDD 100 31 37 38 5 EEE 50 13 24 29 6 FFF 50 11 22 27 7 GGG 100 18 28 32 8 HHH 200 27 34 36 9 JJJ 500 46 45 44 10 KKK 1000 45 45 44 Total 2500 400 400 400

The multiple weighting method and the index weighting method, as described above, are embodiments of the invention which operate in two dimensions: time and volume. However, the invention can operate in three, four, or more dimensions, with each dimension contributing to the allocation of incoming order to the resting orders in the central order book.

For example, certain market participants, such as a lead market maker or a designated market maker, may carry out pre-defined or specialized roles in the market. (Exchanges often employ many terms for market participants who perform specialised roles. Lead Market Makers are often also referred to as Specialists or Primary Market Makers. Designated Market Makers may also be referred to as Competing Market Makers.) Such participants could have their allocations weighted in accordance with their role. Prioritizing allocation in accordance with the trader's role is often referred to as preferencing. Accordingly, in the following example, a preference value is assigned to each buy order and each sell order to reflect the role of the trader behind the order. Referring to Equation 7, the following algorithm implements the additional dimension of preferencing into the algorithm for index weighting method described above. For each resting order n (sorted in order of time entered into the order book) with volume v_(n) lots and preference value p_(n) in a total of N orders, the pro-rata factor f_(n) is calculated as follows:

$\begin{matrix} {f_{n} = {{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)}^{\frac{w_{v}}{S}} \times \left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)^{\frac{w_{t}}{S}} \times \left( p_{n} \right)^{\frac{w_{p}}{S}}}} & {{Equation}\mspace{14mu} 7} \end{matrix}$

The allocation A_(n) for each resting order n against incoming order of volume R lots is calculated as follows:

$\begin{matrix} {A_{n} = {{MIN}\left( {v_{n},{\frac{f_{n}}{\sum\limits_{r = 1}^{N}f_{r}} \times R}} \right)}} & {{Equation}\mspace{14mu} 8} \end{matrix}$

The MIN( ) function ensures that the allocation for resting order n does not exceed the volume v of the order.

KEY—Parameters

-   N Number of Resting Buy (Sell) Orders     -   Sorted by Time—each n=1 (first) to N (last) -   v_(n) Volume of Each Resting Order n -   w_(v) Weighting of Volume Pro-Rata Element -   w_(t) Weighting of Time Pro-Rata Element -   p_(n) Preference Value of Each Resting Order n -   w_(p) Weighting of Preferencing Element -   C Time offset (generally set to 1) -   S Smoothing factor (smoothing increases with S) -   f_(n) Pro-rata factor for Resting Buy (Sell) Order n -   A_(n) Allocation for Resting Buy (Sell) Order n -   R Incoming Sell (Buy) Order Volume

Referring also to FIG. 7, the data shown in Table 8 is depicted graphically to compare the allocation profile with no preferencing with the allocation profile where the overall preference weighting is set to one (1), thus demonstrating how the preference values adjust the allocation profile in accordance with the trader's role. Trader GGG is assigned Lead Market Maker status with a preference value of five (5), and Traders CCC and HHH are assigned Designated Market Maker status, each with a preference value of two (2). All other traders have a standard preference value of one (1). The volume weight parameter and time weight parameter, W_(v) and W_(t) respectively, are each set to one (1) in this example.

TABLE 8 Resting W_(v) = 1; W_(v) = 1; Preference Order W_(t) = 1 No W_(t) = 1 With Time Value Volume Preferencing Preferencing (n) Trader (p) (v) (lots) (W_(p) = 0) (W_(p) = 1) 1 AAA 1 200 91 68 2 BBB 1 200 82 61 3 CCC 2 100 36 55 4 DDD 1 100 31 23 5 EEE 1 50 13 10 6 FFF 1 50 11 8 7 GGG 5 100 18 68 8 HHH 2 200 27 41 9 JJJ 1 500 46 33 10 KKK 1 1000 45 33 Total 400 400 400

While the present invention has been described with respect to what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. For example, although the invention is primarily described with respect to trading futures contracts, the invention is equally applicable to trading other derivatives, options contracts, or cash-based financial instruments such as equities. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 

1. A system for facilitating trading of financial instruments in a market, the system comprising: a server at which financial instruments are traded; and an interface in communication with the server, the interface being configured to receive entry of at least one of a buy order and a sell order, each buy order and each sell order having a price, a volume, and an entry time and relating to a respective financial instrument; wherein the server is configured to receive a plurality of buy orders and sell orders from the interface, and to match buy orders relating to a first financial instrument and having a first price to sell orders relating to the first financial instrument and having the first price by, for each buy order and each sell order, using the volume and entry time to assign a volume weight and a time weight, and using the volume weights and the time weights to determine each match; and wherein the server is further configured to use each determined match to complete a respective trade, and wherein the server is further configured to determine each match according to a first algorithm which is expressible as $f_{n} = \frac{{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)} + {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}}{w_{v} + w_{t}}$ wherein each buy or sell order relating to the first financial instrument is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first financial instrument; v_(n)=a volume of the n^(th) buy or sell order; r=a whole number greater than or equal to 1 and less than or equal to N; v_(r)=a volume of the r^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order.
 2. A system for facilitating trading of financial instruments in a market, the system comprising: a server at which financial instruments are traded; and an interface in communication with the server, the interface being configured to receive entry of at least one of a buy order and a sell order, each buy order and each sell order having a price, a volume, and an entry time and relating to a respective financial instrument; wherein the server is configured to receive a plurality of buy orders and sell orders from the interface, and to match buy orders relating to a first financial instrument and having a first price to sell orders relating to the first financial instrument and having the first price by, for each buy order and each sell order, using the volume and entry time to assign a volume weight and a time weight, and using the volume weights and the time weights to determine each match; and wherein the server is further configured to use each determined match to complete a respective trade, and wherein the server is further configured to determine each match according to a second algorithm which is expressible as $f_{n} = {{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)}^{\frac{w_{v}}{S}} \times \left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)^{\frac{w_{t}}{S}}}$ wherein each buy or sell order relating to the first financial instrument is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first financial instrument; v_(n)=a volume of the n^(th) buy or sell order; r=a whole number greater than or equal to 1 and less than or equal to N; v_(r)=a volume of the r^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; S=a smoothing factor; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order.
 3. The system of claim 1, wherein each buy order and each sell order is assigned at least a third weight value relating to a third characteristic, and wherein the server is further configured to use at least the assigned third weight values in conjunction with the assigned volume weights and the assigned time weights to determine each match.
 4. The system of claim 3, wherein the third characteristic comprises an association with a trader and the third weight value comprises a preference value relating to the associated trader.
 5. The system of claim 1, wherein the server is further configured to assign the volume weights and the time weights by using observable data relating to the market.
 6. The system of claim 5, wherein the server is further configured to adjust at least one of the previously assigned volume weights and the time weights by using observable data relating to the market.
 7. A method of trading of financial instruments in a market, the method comprising the steps of: receiving from a plurality of users entry of buy orders and sell orders, each buy order and each sell order having a price, a volume, and an entry time and relating to a respective financial instrument; using a computer to assign a volume weight and a time weight to each buy order relating to a first financial instrument and having a first price based on its respective volume and entry time; using a computer to assign a volume weight and a time weight to each sell order relating to the first financial instrument and having the first price based on its respective volume and entry time; using a computer to match buy orders having the first price to sell orders having the first price using the assigned respective volume weights and time weights; and using the matched buy orders and sell orders to complete at least one trade, wherein the step of using a computer to match buy orders to sell orders further comprises using the assigned respective volume weights and time weights according to a first algorithm which is expressible as $f_{n} = \frac{{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)} + {w_{t}\left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)}}{w_{v} + w_{t}}$ wherein each buy or sell order relating to the first financial instrument is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first financial instrument; v_(n)=a volume of the n^(th) buy or sell order; r=a whole number greater than or equal to 1 and less than or equal to N; v_(r)=a volume of the r^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order.
 8. A method of trading of financial instruments in a market, the method comprising the steps of: receiving from a plurality of users entry of buy orders and sell orders, each buy order and each sell order having a price, a volume, and an entry time and relating to a respective financial instrument; using a computer to assign a volume weight and a time weight to each buy order relating to a first financial instrument and having a first price based on its respective volume and entry time; using a computer to assign a volume weight and a time weight to each sell order relating to the first financial instrument and having the first price based on its respective volume and entry time; using a computer to match buy orders having the first price to sell orders having the first price using the assigned respective volume weights and time weights; and using the matched buy orders and sell orders to complete at least one trade, wherein the step of using a computer to match buy orders to sell orders further comprises using the assigned respective volume weights and time weights according to a second algorithm which is expressible as $f_{n} = {{w_{v}\left( \frac{v_{n}}{\sum\limits_{r = 1}^{N}v_{r}} \right)}^{\frac{w_{v}}{S}} \times \left( \frac{\left( {N + C} \right) - n}{\sum\limits_{r = 1}^{N}r} \right)^{\frac{w_{t}}{S}}}$ wherein each buy or sell order relating to the first financial instrument is assigned a value of n based on a time order of receipt; N=a total number of buy or sell orders relating to the first financial instrument; v_(n)=a volume of the n^(th) buy or sell order; r=a whole number greater than or equal to 1 and less than or equal to N; v_(r)=a volume of the r^(th) buy or sell order; C=a time offset; w_(v)=the assigned volume weight; w_(t)=the assigned time weight; S=a smoothing factor; and f_(n)=a resultant pro-rata factor for the n^(th) buy or sell order.
 9. The method of claim 7, the method further comprising the step of using a computer to assign at least a third weight value to each buy order and to each sell order, the third weight value relating to a third characteristic, and wherein the step of using a computer to match buy orders to sell orders further comprises using a computer to match buy orders having the first price to sell orders having the first price using the assigned respective volume weights, time weights, and at least third weight values.
 10. The method of claim 9, wherein the third characteristic comprises an association with a trader and the third weight value comprises a preference value relating to the associated trader.
 11. The method of claim 7, wherein the step of using a computer to assign the volume weight and the time weight to each buy order further comprises using a computer to assign the volume weight and the time weight to each buy order by using observable data relating to the market.
 12. The method of claim 11, further comprising the step of, for at least one buy order, using a computer to adjust at least one of the previously assigned volume or time weights by using observable data relating to the market.
 13. The method of claim 7, wherein the step of using a computer to assign the volume weight and the time weight to each sell order further comprises using a computer to assign the volume weight and the time weight to each sell order by using observable data relating to the market.
 14. The method of claim 13, further comprising the step of, for at least one sell order, using a computer to adjust at least one of the previously assigned volume or time weights by using observable data relating to the market. 